<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style>
    .outer {
        display: flex;
        justify-content: center;
        align-items: center;
        flex-wrap: wrap;
        border: 1px solid aqua;
        width: 400px;
    }
    .item1 {
        width: 100px;
        height: 100px;
        border: 1px solid red;
    }
    .item2 {
        width: 200px;
        flex-basis: 0;
        height: 100px;
        border: 1px solid blueviolet;
    }
    .item3 {
        width: 200px;
        height: 100px;
        flex-basis: 300px;
        border: 1px solid green;
    }
</style>
<body>
<div class="outer">
    <div class="item1">1</div>
    <div class="item2">2</div>
    <div class="item3">3</div>
</div>
</body>
</html>
